1. Field of the Invention
The present invention generally relates to an aerial transport system having a self-propelled vehicle or carriage, such as a tramway or cableway. More specifically, the invention relates to an improvement in a means for controlling an electric power supply for the vehicle or carriage, in which the means includes a means for detecting a vehicle or carriage position in the aerial tramway or cableway. Further, the invention relates to an improvement in a vehicle or carriage position detecting means capable of detecting a position of the vehicle or carriage on the track. The invention yet further relates to a control system for controlling an electric power supply for the vehicle or carriage and being co-operative with the vehicle or carriage position detecting means.
2. Description of the Prior Art
The aerial transport system, such as a tramway or cableway system, generally comprises a tramway or cableway, a self-propelled vehicle or carriage, having electrical driving means moving the tramway or cableway, and an electric power supplying means including a pair of electric current-carrying cables which are positioned apart from one another and in parallel relationship with respect to each other and the tramway or cableway.
One of the typical and general constructions of the aerial transport system will be schematically illustrated and shown in FIG. 1. In FIG. 1, a cable 1, for supporting a carriage 2 and defining a cableway is supported by stationary towers (not shown) arranged at regular intervals along the cableway. A pair of electric current-carrying cables 3 are supported by the supporting cable 1 by means of known suspension members such as a plurality of brackets (not shown).
The carriage 2 has driving wheels 4 engaging or riding on the supporting cable 1 so as to suspend the carriage 2 through suspension member 5 and move the carriage 2 along the tramway or cableway. The carriage 2 has an electric current collecting means 7 including current collecting shoes 8 for sliding contact with the current-carrying cables 3 and collecting electric power from the cables 3. The carriage 2 has an electric driving means, such as an electric driving motor (not shown), to be driven by the electric power collected by the current collecting means 7. Thus, the vehicle or carriage is propelled to move along the tramway or cableway by the driving means whose driving power is transmitted to the driving wheels through transmission means (not shown). Practically, in such a self-propelled vehicle or carriage, the transmission means is received within the suspension member 5.
In a transport system such as the aforementioned, the operation of the carriage or vehicle is generally performed under an automatic centralized control system without a driver riding in each carriage or vehicle. Therefore, to provide sufficient safety or security in operation is one of the most important matters for such a system. To fulfill safety requirements, the carriage or vehicle is provided with a automatic braking device, such as an electromagnetic brake, which is operative when power is not supplied to the carriage or vehicle.
The current-carrying cables are separated or divided at regular intervals to define, independent power supply zones. In each power supply zone, there is provided a means for controlling the power supply with respect to carriage or vehicle positions in the tramway or cableway; namely, the control means operates to cut the power supply for the carriage or vehicle so as to actuate the braking device, when the preceding carriage is in an adjacent zone.
A typical and general electric power supply control system is schematically illustrated and shown in FIG. 2. A pair of current-carrying cables 22, 24 are respectively separated or divided by insulating members 26 at regular intervals so as to define, respectively independent power supply zones I, II, III . . . The following explanation applies, by way of example, to the power supply to zone I; only the corresponding control circuit for zone I is shown in FIG. 2. Respective current-carrying cables 22, 24 are connected to power supply cables 28, 30 respectively through a power supply controlling circuit 40. The power supply control circuit 40 is connected to a holding relay circuit 50. The holding relay circuit 50 is connected to carriage or vehicle position detecting means 62, 64 provided in the power supply zones II and III. In FIG. 2, the detecting means 62 in the zone II is connected to a reset-input R of the holding relay circuit 50; the detecting means 64 in the zone III is connected to a set-input S of the holding relay circuit 50. Thus, when the detecting means 62 detects a vehicle or carriage in the zone II, the holding relay circuit 50 is put in the OFF position so as to actuate the power supply control circuit 40 for breaking the power supply to the zone I. When the carriage or vehicle leaves zone II and is detected in zone III by the detecting means 64, the holding relay circuit 50 goes into the ON position and the power supply control circuit 40 supplies power to the current-carrying cables 22, 24 in the zone I. This position of the holding relay circuit 50 is maintained until the next occasion when the carriage or vehicle position detecting means 62 of the zone II detects the following carriage or vehicle in the zone II.
The power supply control circuit 40 according to the prior art will be schematically illustrated and shown in FIG. 3. The current-carrying cables 22, 24 are connected to the power cables 28, 30 through circuit breakers 42, 44 and contacts 46, 47 of a contactor 48. The contactor 48 is operated or controlled by a contact 52 of the holding relay 50.
In practice, circuit breakers and/or a contact 46 or 47 need only be provided in one of the leads connecting the power cables and the current-carrying cables. However, FIG. 3 shows circuit breakers and contacts being provided on both leads, as in the usual manner.
The carriage 2 travels through the cableway with the current collecting means 7. The current collecting means 7 includes the current collecting shoes 8 contacting the current-carrying cables 22, 24. An electric current thus flows through the power supply circuit to the driving means 9 of the carriage.
Upon the absence of a prior carriage in the adjacent forward zone, the holding relay circuit 50 operates so as to close the contact 52. The contactor 48 is then excited to close the contacts 46, 47 so that electric power can be supplied to the respective current-carrying cables 22, 24 from the power cables 28, 30.
If there is a prior carriage in the adjacent forward zone, the holding relay circuit 50 is inoperative, thereby opening contact 52. The contactor 48 is not excited and thus opens the contacts 46, 47. The electric power supply circuit is thus broken to cease supplying power to the current-carrying cables 22, 24. If there is a carriage in the present zone, it may be stopped by actuating the automatic braking device, such as the electromagnetic brake (not shown) mounted on the carriage.
The automatic braking device has a braking member which can be pressed against the driving wheels or driving means by a spring, when an actuation means of the braking device is not energized. When the electric power is not supplied to the brake means, the actuation means is inoperative. Thereby, the brake means is free from the force of the actuation means so as to contact the driving wheels and so on. Preferably, the automatic braking device may also be actuated when less than a predetermined current is supplied.
Meanwhile, to control the power supply to the independent zones I, II, III . . . in the aerial transport system, it is necessary to detect whether or not a vehicle or carriage is present within each zone. Therefore, there are provided vehicle or carriage position detecting means 60, 62, 64 . . . , in zones I, II, III . . . , respectively, as shown in FIG. 2.
In the prior art, there are various vehicle or carriage position detecting systems. One of the systems comprises one or more limit switches mounted on arms of cable supporting brackets which support the current-carrying cable in each power supplying zone. A flange portion of the wheels of the vehicle or carriage contacts at least one of the switching arms of the limit switches so as to actuate the same. Another system comprises one or more proximity switches mounted on the arms of cable supporting brackets in each power supplying zone. The proximity switch actuates when the lower portion of the current collecting means of the vehicle or carriage passes through the nearest point to the switch.
In the prior systems, the limit switches or proximity switches are mounted on the arms of the brackets which are positioned at high elevations and which may cause danger, inconvenience and further problems in mounting or mending the same. Further, the limit switches or proximity switches merely detect passing of the vehicle or carriage at the points where they are provided. Therefore, the switches may not detect for example a stationary carriage which has broken down in the power supplying zone. For accuracy in controlling the power supply, further scanning systems have been required, for example an electric sensing system of the vehicle or carriage position.
The present invention aims to improve the afore-mentioned disadvantages and difficulties in the prior art and to provide a novel and useful vehicle or carriage position detecting means which can detect whether or not there is a vehicle or carriage within the zone. Further, the invention aims to provide a control system for controlling the electric power supply to the zone, and thus control the driving of the vehicle or carriage.